00MAIN I. SIDEROUS. 



portions of pure air, and frequently of water 

 also and fixed air, 



" One hundred parts metallic iron are 

 capable of taking up 66 or 70 of pure ail 4 . 

 When 100 parts iron contain but 40 of this 

 air, the compound is still magnetic/' His 

 table of the fusibility of the simple earths 

 presents some curious experiments on the 

 mixture of calcined iron and rust of iron* 

 with other substances, which show the 

 power of this metal. Even when it only 

 amounts to four parts in the hundred, it 

 sensibly influences the compound. 



Sidegea, or siderous earth, is so generally 

 diffused, that almost every mineral sub- 

 stance derives its colour from it, from a 

 pale blue to the deepest red* Animal sub- 

 stances contain it ; and it exists in the ve- 

 getable kingdom, even in plants apparently 

 supported merely by air and water. It 

 would appear that even the atmosphere 

 abounds with atoms of iron, whence per- 

 haps the meteoric stones. 



